Flood defense apparatus, system and method

ABSTRACT

A flood defense apparatus including a channel  10  having a base  12  and side walls  14, 16  extending downwardly from a surface level opening  36  to the base  12  so as to be adapted to collect and transfer surface liquid, a channel dividing formation  18  extending generally downwardly from the opening of the channel towards but not to the base, so as to divide the channel into a drainage portion  20  open for the access flow of surface liquid and a chamber portion  22  and to define a liquid communicating portion  24  between the drainage portion and the chamber portion below the dividing formation, and at least one buoyant barrier member  26  received in the chamber portion to be selectively moveable between a first position within the channel and a second position where the barrier member at least partially extends from the channel. The level of liquid in the drainage portion follows the level of liquid in the chamber portion to allow, in use, varying levels of liquid in the channel to move the barrier member reversibly between the first position and the second position.

TECHNICAL FIELD

The present invention relates generally to flood defense apparatus forprotecting land or buildings and more particularly to flood defenseapparatus for installation in the vicinity of land or buildings whichare susceptible to flooding by surface liquid, such as rainwater.

BACKGROUND

Flood defense apparatus are known. Known apparatus make use ofcomplicated mechanical, hydraulic or pneumatic means to raise and lowera moveable flood barrier in times of high water. For example, EP0726364provides an apparatus for a watercourse, such as a dike, having amoveable flood barrier. In times of high water, the flood barrier can betransferred from a low position towards a high position by water flowinginto a chamber within the dike body down an inclined filling channel. Asthe water level lowers, water flows from the chamber via a dischargechannel and the flood barrier moves towards the low position. Thefilling channel is provided in an upper part of the dike body and thedischarge channel is provided in a lower part of the dike body.

This apparatus requires a permanent, above ground structure, such as adike body. The dike body is both intrusive and an eye sore and is apermanent barrier when water is not present. For example, pedestrians orvehicles are prevented from moving over the barrier when in the lowposition when there is no risk from flood water. Installation of theapparatus is expensive and time consuming and is limited in itsapplication. Flood water must rise significantly above ground levelbefore the flood barrier is raised.

SUMMARY

A first aspect of the present invention provides a flood defenseapparatus, comprising:

-   -   a channel having a base and side walls extending downwardly from        a surface level opening to the base so as to be adapted to        collect and transfer surface liquid;    -   a channel dividing formation extending generally downwardly from        the opening of the channel towards but not to the base, so as to        divide the channel into a drainage portion open for the access        flow of surface liquid and a chamber portion and to define a        liquid communicating portion between the drainage portion and        the chamber portion below the dividing formation; and    -   at least one buoyant barrier member received in the chamber        portion to be selectively moveable between a first position        within the channel and a second position where the barrier        member at least partially extends from the channel.

Advantageously, the channel is adapted to collect and transfer surfaceliquid from above surface level. Surface liquid may access the channelat least via the drainage portion. Surface liquid is allowed to flowinto the channel and be transferred or drained away in a similar mannerto an existing drainage channel or gutter, an upper opening of which isprovided at ground level.

Where the level of liquid in the channel is below the channel dividingportion, the barrier member is in the first position, and liquid in thechannel is entirely within the communicating portion. The communicatingportion conveniently allows liquid to flow freely along the base of thechannel to be suitably transferred. Liquid collected in the channel maysoak away into surrounding earth or a fluid outlet may be provided nearthe base of the channel and a suitable drainage means attached thereto.The channel conveniently provides an immediate drain for surface liquidto flow, even where the amount of liquid entering the channel is notenough to sufficiently fill the chamber portion and raise the barriermember received therein.

Where a substantial volume of liquid flows into the channel and thelevel of liquid therein rises up the channel beyond the lowest extent ofthe dividing formation, liquid enters the chamber portion and moves thebuoyant barrier member received therein towards the second position. Theliquid level in the chamber portion follows liquid level in the drainageportion to allow, in use, varying levels of liquid in the channel tomove the barrier member reversibly between the first position and thesecond position. Liquid may still be transferred along the channelwhilst the barrier member is being moved by liquid rising in the chamberportion.

The apparatus therefore acts as a conventional drainage channel when theliquid level in the channel is below the channel dividing formation andwhen the level of liquid in the channel is sufficient to enter thechamber portion and move the barrier member towards the second position.

Advantageously, the apparatus is suitable for many applications whichrequire protection from surface liquid, such as domestic and commercialbuildings, car parks or agricultural land. The source of the surfaceliquid may include tidal watercourses, excess rain water or accidentalspillage.

Preferably the channel dividing formation is elongate and arranged alongthe channel. The channel dividing formation may be arranged in thechannel and orientated in a number of ways. For example, the channeldividing formation may divide the channel approximately in half.Suitably the channel dividing formation may extend vertically towardsthe base of the channel or may be angled relative to the vertical. Thechannel dividing formation may be removable from the channel to allowaccess to the barrier member, for example.

Preferably the chamber portion is defined by at least the channeldividing formation and a first side of the channel in a similar manner,the drainage portion is defined by the channel dividing formation andthe opposing second side of the channel.

Conveniently the chamber portion is defined by a chamber housingcomprising at least the channel dividing formation and a further sidewall formation spaced apart therefrom, and comprising means for the atleast one barrier member to be received therein.

Preferably the at least one barrier member is slideably mounted in thechamber housing to engage with one or both of the channel dividingformation and the further side wall formation. Suitable projections andcomplementarily shaped recesses may be provided on the barrier memberand in the chamber housing respectively. Such engagement may suitablyprovide guide means to the barrier member when moving between the firstand second positions.

Suitably the chamber housing may comprise end walls extending betweenthe channel dividing formation and the further side wall formation. Theend walls may be adapted to allow two or more chamber housings toconnect together. Suitably the end walls comprise connecting portions toallow a plurality of chamber housings to be connected together. Forexample, one end wall may comprise a projecting portion whichinterconnects with a complementarily shaped recess in a second end wallof a chamber housing of another apparatus. Such connecting apparatus mayconveniently provide an elongate flood defense system.

Preferably the barrier member is in sealing engagement with the chamberhousing when, in use, reversibly moving between the first and secondpositions. The barrier member suitably engages in sealing manner withone or more of the channel dividing formation, further side wallformation and end walls. Sealing engagement between the barrier memberand the chamber housing advantageously prevents liquid from the chamberleaking past the barrier member to surface level and, in particular, aprotected side of the apparatus.

Suitably the chamber housing comprises a base member by which thebarrier member is supported when in the first position. The base membermay simply comprise one or more brackets extending between the channeldividing formation and the first side of the channel. Alternatively, thebase member may extend substantially between the channel dividingformation and the further side wall formation, the base having one ormore apertures to allow liquid to enter the chamber housing when thelevel of liquid in the channel rises up beyond the lower extent of thechannel dividing formation.

Suitably the barrier member comprises a buoyant lower portion. A buoyantlower portion ensures the barrier member is being urged from belowtowards the second position by rising liquid in the chamber portion.

Suitably the buoyant lower portion has a volume which is greater than avolume of an upper portion of the barrier member. Suitably the barriermember is at least partly hollow. A hollow barrier member isconveniently lightweight and particularly buoyant.

Suitably the barrier member comprises a vertical face and an opposingangled face to define a barrier member having a wedge-like crosssection. Suitably, in use, the angled face may be a ‘wet’ side of thebarrier member relative to surface liquid accessing the channel and thevertical face may be a ‘dry’ side of the barrier member relative tosurface liquid entering the channel from which protection is beingprovided by the apparatus. This arrangement provides a strong barriermember to withstand the loads exerted on the barrier member by surfaceliquid, particularly when the level of the surface liquid is highrelative to the barrier member when in the second position. The loadsexerted on the barrier member by a high level of surface liquid will begreater on the lower portion of the barrier member than the loads on theupper portion of the barrier member.

Suitably the barrier member and chamber housing may be complementarilyshaped to provide sealing engagement therebetween as the barrier memberreversibly moves between the first and second positions. A barriermember having a wedge-shaped cross section provides an effective sealwhen engaged with a complementarily shaped chamber housing, particularlywhen the barrier member is in the raised second position.

Suitably the apparatus may comprise a channel cover having a firstapertured area to correspond with the drainage portion for surfaceliquid to drain and a second apertured area adapted to correspond withthe chamber portion. The first and second apertured areas may compriseslots arranged along opposing sides of the channel cover. The channelcover desirably provides a suitable and safe surface for pedestrians towalk over or vehicles to move over.

A closure member may be provided to close the second apertured area whenthe barrier member is in the first position. Suitably the closure membermay be mounted to the channel cover by a hinge. A hinged closure memberprevents the ingress of debris, such as leaves, into the chamber housingwhen the barrier member is in the first position within the channelwhilst allowing the barrier member to move towards the second positionto at least partially extend from the channel.

The first apertured area in the cover may comprise a plurality ofdrainage apertures. The drainage apertures may be equally spaced. Thedrainage apertures may be parallel slots. The drainage apertures may bearranged and adapted to prevent the ingress of debris, e.g. leaves,whilst allowing surface liquid to access the channel.

Suitably the a portion of the base of the channel is sloped. The basemay be sloped longitudinally and/or transversely relative to thechannel. Preferably the base is sloped transversely from a side of thechannel towards a deepest point of the channel. A sloped baseadvantageously prevents the channel silting up to ensure an unobstructedchannel is provided for the surface liquid to flow.

Suitably at least one of the channel sides, channel base, channeldividing formation and barrier member may be formed from a plasticsmaterial. Suitably a plastics material provides resistance to corrosionand is lightweight. A lightweight apparatus also provides for easyinstallation. A suitable plastic may include urethane.

Alternatively the channel sides and/or channel base may be concrete.

In a first embodiment of the invention, the channel sides and basecomprise the sides and base of an optionally lined, sub-surface channelexcavation.

In a second embodiment of the present invention, a channel module isprovided for fitting in a sub-surface channel excavation, the channelmodule comprising:

-   -   a channel lining having a base and side walls extending        downwardly from an opening, for example to be located at a        surface level in use, to the base so as to define a channel        adapted to collect and transfer surface liquid;    -   a channel dividing formation extending generally downwardly from        the opening of the channel lining towards but not to the base,        so as to divide the channel lining into a drainage portion open        for the access flow of surface liquid and a chamber portion and        to define a liquid communicating portion between the drainage        portion and the chamber portion below the dividing formation;        and    -   at least one buoyant barrier member received in the chamber        portion to be selectively moveable between a first position        within the channel lining and a second position where the        barrier member at least partially extends from the channel        lining.

The sub-surface channel excavation may be an existing drainage channel,e.g. a prefabricated concrete drainage channel, or may be purposivelyexcavated for the channel module to be fitted. For example, the channelmodule may conveniently be fitted into an existing drainage channel ormay be retrofitted around an existing building or installed in anexcavated channel when the building is built. Suitably the channelmodule is sized according to the size of the sub-surface channelexcavation in which it is to be fitted in, for example where the channelis an existing channel, or the sub-surface channel excavation issuitably sized in accordance with the channel module, for example achannel specifically excavated for the channel module. Suitably thechannel module sits in the channel and is flush with the surface level,the only visible aspect being the opening of the channel lining. Thisallows surface fluid to drain into the channel lining. The channelmodule operates in the same manner as the apparatus as described above.

Preferably the channel module further comprises first and second endwalls adapted to allow the first end wall of a channel module to connectto the second end wall of another channel module to allow a plurality ofchannel modules to connect together. A first end wall may becomplementarily shaped with a corresponding second end wall. The channeldividing formation is preferably mounted or attached to the end walls.Suitably the channel dividing formation may be removable from thechannel module to allow access to channel lining or barrier member, forexample. The channel dividing formation may be slideably mounted to thechannel lining and engage with downwardly extending slots in the endwalls of the module, for example.

Preferably the first end wall of the channel module comprises a fluidinlet adapted to sealably engage with a fluid outlet provided in thesecond end wall of another channel module. Suitably the fluid inlet andfluid outlet being provided near the base of its corresponding channelmodule. Conveniently, a plurality of channel modules may be fluidlyconnected in series to provide a continuous flow path for surface liquidto be transferred. Suitably the chamber portions of adjacent channelmodules may be fluidly connectable. Suitably the barrier members ofadjacent channel modules may be connectable.

One or more sealing members may be provided to seal a gap betweenadjacent barrier members of neighbouring channel modules.

In a further aspect of the present invention, the channel mayconveniently be an existing drainage channel, e.g. a prefabricatedconcrete drainage channel, into which at least the channel dividingmember is fitted to define the chamber portion in which at least onebarrier member is received.

This aspect of the invention provides a flood defense kit for fittinginto an existing drainage channel to create a flood defense apparatus asdescribed above, the kit comprising:

-   -   a channel dividing formation extending generally downwardly from        an opening of the channel towards but not to the base, so as to        divide the channel into a drainage portion open for the access        flow of surface liquid and a chamber portion and to define a        liquid communicating portion between the drainage portion and        the chamber portion below the dividing formation; and    -   at least one buoyant barrier member received in the chamber        portion to be selectively moveable between a first position        within the channel and a second position where the barrier        member at least partially extends from the channel.

The channel may be an excavated channel or may be a prefabricatedchannel which is arranged in an excavated channel. The channel may be anexisting channel or may be excavated during construction of a building,for example, or where the apparatus is retrofitted to protect anexisting building or plot of land.

Suitably the channel dividing formation is suspended from a channelcover. Alternatively, the channel dividing formation may be attached toend walls of the channel. As described above, the channel dividingformation divides the channel into a drainage portion and a chamberportion in which the barrier member is received. The drainage portionand chamber portion are fluidly connected by the communicating portionto allow liquid to enter the chamber portion when the liquid level inthe channel is sufficient. The liquid level in the chamber housingfollows liquid level in the drainage portion to allow, in use, varyinglevels of liquid in the channel to move the barrier member reversiblybetween the first position and the second position. The communicatingportion below the channel dividing formation conveniently allows anylevel of liquid to be transferred along the channel and drained to soakfrom the channel or via suitable drainage means.

A further aspect of the present invention provides a flood defensesystem comprising a plurality of apparatus or channel modules asdescribed above disposed serially, and for example connected in series,to define an elongate flood defense system. The flood defense system maybe provided in front of or around an area of a building to be protected.An apparatus or system may be provided in the vicinity of weak areas ofa building, such as doors and windows, for example. Advantageously, thebarrier member does not require support means when moving from the firstposition to the second position, such as undesirably using the buildingas the support means. The building may be domestic or commercial. Thesystem may be retrofitted around an existing building or installed whenthe building is initially built. The system may be provided betweenflood resistant walls to provide an access point or gateway when thebarrier member is in the lowered first position whilst providing acontinuous flood barrier with the walls when the barrier member is inthe raised second position.

One or more sealing members may be provided to seal a gap betweenadjacent barrier members of neighbouring adjoined apparatus or modules.

A further aspect of the present invention provides a drainage systemcomprising an apparatus or a system as described above.

A further aspect of the present invention provides a method ofinstalling a flood defense apparatus, comprising the steps of:

-   -   providing a drainage channel having a base and side walls        extending downwardly from a surface to the base so as to be        adapted to collect and transfer surface liquid;    -   providing a channel dividing formation extending generally        downwardly from an opening of the channel towards but not to the        base, so as to divide the channel into a drainage portion open        for the access flow of surface liquid and a chamber portion and        to define a liquid communicating portion between the drainage        portion and the chamber portion below the dividing formation;    -   providing at least one buoyant barrier member received in the        chamber portion to be selectively moveable between a first        position within the channel to a second position where the        barrier member at least partially extends from the channel;    -   whereby liquid level in the chamber portion follows liquid level        in the drainage portion to allow, in use, varying levels of        liquid in the channel to move the barrier member reversibly        between the first position and the second position.

The method may further comprise the step of connecting two or more flooddefense apparatus together in fluid communication to provide a flooddefense system.

The method may further comprise the step of providing one or moresealing members to seal a gap between adjacent barrier members ofneighbouring apparatus.

In a possible embodiment, the method of the invention provides a methodof installing a channel module into a sub-surface channel excavation isprovided, the method comprises the steps of:

-   -   providing a channel module comprising:    -   a channel lining having a base and side walls extending        downwardly from a surface so as to be adapted to collect and        transfer surface liquid;    -   a channel dividing formation extending generally downwardly from        an opening of the channel lining towards but not to the base, so        as to divide the channel lining into a drainage portion open for        the access flow of surface liquid and a chamber housing and to        define a liquid communicating portion between the drainage        portion and the chamber portion below the dividing formation;        and    -   at least one buoyant barrier member received in the chamber        housing to be selectively moveable between a first position        within the channel lining and a second position where the        barrier member at least partially extends from the channel        lining; and    -   installing the channel module in the sub-surface channel        excavation.

The method of installing a channel module into a sub-surface channelexcavation may further comprise one or more of the following steps:

-   -   providing a cover having a first aperture for surface liquid to        drain and a second aperture adapted to correspond with the upper        opening of the chamber housing;    -   connecting two or more channel modules together in fluid        communication to provide a flood defense system; and    -   providing one or more sealing members to seal a gap between        adjacent barrier members of neighbouring apparatus.

In another possible embodiment, the method of the invention provides amethod of installing a flood defense kit into an existing drainagechannel to create a flood defense apparatus as described above, thechannel having a base and side walls extending downwardly from a surfaceso as to be adapted to collect and transfer surface liquid, comprisingthe steps of:

-   -   providing a channel dividing formation extending generally        downwardly from an opening of the channel towards but not to a        base, so as to divide the channel into a drainage portion open        for the access flow of surface liquid and a chamber portion and        to define a liquid communicating portion between the drainage        portion and the chamber portion below the dividing formation;        and    -   slideably mounting at least one buoyant barrier member in the        chamber portion to be selectively moveable between a first        position within the channel to a second position where the        barrier member at least partially extends from the channel;

whereby liquid level in the chamber portion follows liquid level in thedrainage portion to allow, in use, varying levels of liquid in thechannel to move the barrier member reversibly between the first positionand the second position.

The channel may be a channel excavated in front of or around the area ofa building to be protected. Alternatively, the channel may be anexisting drainage channel, as described above. Desirably, the channel isa depth and width to allow the barrier member to be wholly contained inthe channel when in the first position to provide a flat upper surfacelevel with the ground surface.

The method of installing a flood defense kit into an existing drainagechannel to create a flood defense apparatus as described above mayfurther comprise any one of the following steps:

-   -   providing a chamber housing comprising at least the channel        dividing formation and a further side wall formation spaced        apart therefrom and adapted to receive the barrier member; and    -   providing a cover having a first aperture for surface liquid to        drain and a second aperture adapted to correspond with the upper        opening of the chamber portion.

The method of installing a flood defense kit into an existing drainagechannel to create a flood defense apparatus as described above mayfurther comprise any one of the following steps:

-   -   connecting two or more chamber housings together in fluid        communication; and    -   providing one or more sealing members to seal a gap between        adjacent barrier members of neighbouring kits.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 is an isometric representation of an embodiment of a channelmodule according to the present invention showing a section through themodule;

FIG. 2 shows an end view of the module of FIG. 1 when the barrier memberis between the first and second positions;

FIG. 3 shows a side of another embodiment of the channel module;

FIG. 4 shows an opposite side of the channel module of FIG. 3;

FIG. 5 shows a plurality of connected barrier members connected;

FIG. 6 shows a flood defense system of channel modules as shown in FIG.4; and

FIG. 7 shows the flood defense system of FIG. 6 with the barrier membersin the raised second position.

DETAILED DESCRIPTION

As shown in FIGS. 1 and 2, a channel module 1 for fitting in asub-surface channel excavation comprises a channel lining 10 having abase 12 and side walls 14, 16 extending downwardly from a surface so asto be adapted to collect and transfer surface liquid, such as rainwater,floodwater or accidental spillage.

A channel dividing formation 18 extends generally downwardly from anopening of the channel lining 10 towards but not to the base 12 so as todivide the channel lining 10 into a drainage portion 20 open for theaccess flow of surface liquid and a chamber portion 22 and to define aliquid communicating portion 24 between the drainage portion 20 and thechamber portion 22 below the channel dividing formation 18. The channeldividing portion 18 and the side wall 16 of the channel lining 10, and achamber base 21, define a chamber housing 22. Conveniently, the channeldividing formation 18 may be removable from the channel module 1 toallow access to the channel lining 10 for cleaning purposes, forexample.

A buoyant barrier member 26 is slideably mounted in the chamber housing22. The chamber housing 22 has an aperture 28 in its base 21 to fluidlyconnect the chamber housing 22 with the drainage portion 20 of thechannel 10. This allows rising liquid in the channel lining 10 to enterand fill the chamber housing 22 and also exit the chamber housing 22when the liquid level in the channel 10 lowers. Liquid level in thechamber housing 22 thereby follows liquid level in the drainage portion20. Therefore, varying levels of liquid in the channel 10 moves thebarrier member 26 reversibly between a first position within the channellining 10 to a second position where the barrier member 26 at leastpartially extends from the channel lining 10. A removable channeldividing formation 18 may also allow access to the barrier member 26 toallow the same to be removed from the channel module 1 for maintenancepurposes, for example.

Advantageously, the channel lining 10 is adapted to collect and transferliquid from ground level. Surface liquid is allowed to flow into thechannel lining 10 and be transferred or drained away in a similar mannerto an existing drainage channel or gutter, an upper opening of which isprovided at ground level. Where excess liquid, such as excess rainwater,flows from the surface into the channel lining 10, the liquid level inthe channel lining 10 rises to enter the chamber housing 22 and move thebarrier member 26 slideably mounted therein towards the second position.

Conveniently, the communicating portion 24 between the drainage portion20 and the chamber housing 22 below the dividing formation 18 allowsliquid to flow freely along the channel lining 10 thereby to be suitablytransferred to ground or via suitable drainage means. Liquid maycontinually be transferred along the channel lining 10 below the channeldividing formation 18 whilst the barrier member 26 is being moved byliquid filling the chamber housing 22. The channel module 1 thereforeacts as a conventional drainage channel for any amount of surfaceliquid, e.g. when the surface liquid entering the channel lining 10 isminimal and when excess surface liquid enters the channel lining 10 andthe barrier member 26 is moved towards the second position, for examplein adverse weather conditions.

The channel module 1 advantageously provides an immediate drain forsurface liquid to flow, even where the amount of liquid entering thechannel lining 10 is not enough to sufficiently fill the chamber housing22 and raise the barrier member 26 mounted therein.

Advantageously, the channel module 1 is suitable for many applicationswhich require protection from surface liquid, such as domestic andcommercial buildings, car parks or agricultural land. The source of thesurface liquid may include tidal watercourses, excess rain water oraccidental spillage.

The barrier member 26 has a wedge-shaped cross section having a verticalface 30 on a protected ‘dry’ side and an angled face 32 on a ‘wet’ sideof the channel module 1. This arrangement provides a strong barriermember 26 to withstand the loads exerted thereon by surface liquid,particularly when the level of the surface liquid is high relative tothe barrier member 26 when in the second position. The barrier member 26is hollow and made from a plastics material such as urethane to providea lightweight and particularly buoyant barrier member 26.

The barrier member 26 engages with the channel dividing formation 18 andside wall 16 of the channel lining 10 which define the chamber housing22 as it moves between the first and second positions. As shown in FIG.5, the barrier member 26 includes projections 52, 54 which engage incomplementarily shaped recesses (not shown) in the channel dividingformation 18 and side wall 16 respectively. This engagement guides thebarrier member 26 between the first and second positions. The engagementis a sealing engagement to prevent liquid from the chamber housing 22leaking past the barrier member 26 to surface level and, in particular,the protected side of the channel module 1. The chamber housing 22 maybe complimentarily shaped with the barrier member 26 to provide aneffective seal therebetween.

A cover 34 is fitted to the opening of the channel lining 10 having afirst slot 36 provided along one side wall 14 of the channel lining 10for surface liquid to drain into the channel lining 10 and a second slot38 provided along an opposite side wall 16 of the channel lining 10adapted to correspond with the upper opening of the chamber housing 22to allow the barrier member 26 to extend from when moving towards thesecond position. A closure member 35 (shown in FIG. 3) may be providedto close the second slot 38 when the barrier member 26 is in the firstposition. The closure member may be mounted to the cover 34 by a hingeor may alternatively be integral with the barrier member 26 to rise andfall therewith. A closure member 35 prevents the ingress of debris, suchas leaves, into the chamber housing 22 when the barrier member 26 is inthe first position. The cover 34 and closure member 35 desirably providea flat surface suitable for pedestrians to walk over and/or vehicles tomove over.

The first slot 36 in the cover 34 includes a plurality of drainageapertures 40. The apertures 40 are equally spaced, parallel slots. Thedrainage apertures 40 prevent the ingress of debris, e.g. leaves, whilstallowing surface liquid to access the channel lining 10. Alternatively,as shown in FIG. 3, the first and second slots may be covered by aseparate cover 33 and closure member 35, respectively. An intermediatecover portion 37 may be provided between the cover 33 and closure member35 to provide a continuous flat surface for pedestrians to walk overand/or vehicles to move over.

A part 13 of the base 12 of the channel lining 10 is sloped transverselyfrom side wall 16 towards a deepest point of the channel lining 10 toadvantageously prevent the build up of silt in the channel lining 10 andto ensure an unobstructed path is provided for the surface liquidentering the channel lining 10 to flow.

The channel lining 10 may be formed from a plastics material. A plasticsmaterial is resistant to corrosion and is lightweight. A lightweightchannel module 1 also provides for easy installation. A suitable plasticmay include urethane.

As shown in FIGS. 3 and 4, the channel module 1 comprises first andsecond end walls 42, 44 adapted to allow the first end wall 42 of achannel module to connect to the second end wall 44 of another channelmodule to allow a plurality of channels modules 1 to connect together inseries to provide an elongate flood defense system. The first end wall42 of one channel module 1 has at least one projecting portion 43 whichis shaped to interconnect with at least one complementarily shapedrecess 45 in the second end wall 44 of another channel module 1 to allowthe channel linings 10 to connect together and provide an elongate flooddefense system 50, as shown in FIGS. 6 and 7. The end walls 42, 44 maycomprise an aperture 45 which allows adjacent chamber housings 22 tofluidly connect together.

As shown in FIG. 5, the barrier members 26 include a projection 47extending along a first vertical side thereof which is adapted tointerconnect with a complementarily shaped recess 49 extending along asecond vertical side of an adjacent barrier member 26 of a neighbouringchannel module 1. Neighbouring channel modules 1 are fluidly connectedto provide a combined drainage channel and flood defense system 50, asshown in FIGS. 6 and 7.

The flood defense system 50 may be provided in front of or around anarea of a building to be protected. One or more channel modules 1 may beprovided in the vicinity of weak areas of a building, such as doors andwindows, for example. Advantageously, the module 1 or system 50 ofconnected modules is substantially maintenance free due to thesimplicity of its automatic operation.

The barrier member 26 does not require support means when moving fromthe first position to the second position, such as undesirably using thebuilding as the support means. The building may be domestic orcommercial. A system 50 of channel modules 1 may be retrofitted aroundan existing building or installed when the building is initially built.The system 50 may be provided between flood resistant walls to providean access point or gateway when the barrier member 26 is in the loweredfirst position whilst providing a continuous flood barrier with thewalls when the barrier member 26 is in the raised second position.

One or more sealing members may be provided to seal a gap betweenadjacent barrier members 26 of neighbouring connected channel modules 1.

To install a channel module 1, as described above, a channel is firstprovided having a base and side walls extending downwardly from asurface so as to be adapted to collect and transfer surface liquid. Thechannel optionally may be lined with plastic or concrete, for example.

Secondly, a channel module 1 as described above is provided andinstalled in the channel. Two or more channel modules 1 may be connectedtogether to provide a flood defense system 50, as described above. Oneor more sealing members may be provided to seal a gap between adjacentbarrier members 26 of neighbouring channel modules 1 in the system 50.

1. A flood defense apparatus comprising: a channel having a base andside walls extending downwardly from a surface level opening to the baseso as to be adapted to collect and transfer surface liquid; a channeldividing formation extending generally downwardly from the opening ofthe channel towards but not to the base, so as to divide the channelinto a drainage portion open for the access flow of surface liquid and achamber portion and to define a liquid communicating portion between thedrainage portion and the chamber portion below the dividing formation;and at least one buoyant barrier member received in the chamber portionto be selectively moveable between a first position within the channeland a second position where the wall member at least partially extendsfrom the channel.
 2. An apparatus according to claim 1, wherein thechamber portion is defined by at least the channel dividing formationand a first side of the channel.
 3. An apparatus according to claim 2,wherein the chamber portion is defined by a chamber housing comprisingat least the channel dividing formation and a further side wallformation spaced apart therefrom, and comprising means for the at leastone barrier member to be received therein.
 4. An apparatus according toclaim 3, wherein the at least one barrier member is slideably mounted inthe chamber housing to engage with one or both of the channel dividingformation and the further side wall formation.
 5. An apparatus accordingto claim 4, wherein the chamber housing comprises end walls extendingbetween the channel dividing formation and the further side wallformation.
 6. An apparatus according to claim 5, wherein the end wallsare adapted to allow a plurality of chamber housings to be connectedtogether.
 7. An apparatus according to claim 4, wherein the chamberhousing comprises a base member by which the barrier member is supportedwhen in the first position.
 8. An apparatus according to claim 3,wherein the barrier member is in sealing engagement with the chamberhousing when, in use, reversibly moving between the first and secondpositions.
 9. An apparatus according to claim 1, wherein the barriermember comprises a buoyant lower portion.
 10. An apparatus according toclaim 9, wherein the barrier member comprises a vertical face and anangled face to define a barrier member having a wedge-like crosssection.
 11. An apparatus according to claim 8, wherein the barriermember and chamber housing are complementarily shaped to provide sealingengagement therebetween as the barrier member reversibly moves betweenthe first and second positions.
 12. An apparatus according to claim 1,wherein the apparatus comprises a channel cover having a first aperturedarea to correspond with the drainage portion for surface liquid to drainand a second apertured area adapted to correspond with the chamberportion.
 13. An apparatus according to claim 12, wherein a closuremember is provided to close the second apertured area when the barriermember is in the first position.
 14. An apparatus according to claim 1,wherein the base of the channel is sloped transversely from a side ofthe channel towards a deepest point of the channel.
 15. An apparatusaccording to claim 1, wherein the channel sides and base comprise thesides and base of an optionally lined, sub-surface channel excavation.16. A flood defense kit for fitting into an existing drainage channel tocreate a flood defense apparatus according to claim 1, the kitcomprising: a channel dividing formation extending generally downwardlyfrom an opening of the channel towards but not to the base, so as todivide the channel into a drainage portion open for the access flow ofsurface liquid and a chamber portion and to define a liquidcommunicating portion between the drainage portion and the chamberportion below the dividing formation; and at least one buoyant barriermember received in the chamber portion to be selectively moveablebetween a first position within the channel and a second position wherethe barrier member at least partially extends from the channel.
 17. Achannel module for fitting in a sub-surface channel excavation to createan apparatus according to claim 1, the channel module comprising: achannel lining having a base and side walls extending downwardly from anopening, for example to be located at a surface level in use, to thebase so as to define a channel adapted to collect and transfer surfaceliquid; a channel dividing formation extending generally downwardly fromthe opening of the channel lining towards but not to the base, so as todivide the channel lining into a drainage portion open for the accessflow of surface liquid and a chamber portion and to define a liquidcommunicating portion between the drainage portion and the chamberportion below the dividing formation; and at least one buoyant barriermember received in the chamber portion to be selectively moveablebetween a first position within the channel lining and a second positionwhere the barrier member at least partially extends from the channellining.
 18. A channel module according to claim 17, further comprisingfirst and second end walls adapted to allow the first end wall of achannel module to connect to the second end wall of another channelmodule to allow a plurality of channel modules to connect together. 19.A channel module according to claim 18, wherein the first end wall ofthe channel module comprises a fluid inlet adapted to sealably engagewith a fluid outlet provided in the second end wall of another channelmodule.
 20. A method of installing a flood defense apparatus, comprisingthe steps of: providing a drainage channel having a base and side wallsextending downwardly from a surface to the base so as to be adapted tocollect and transfer surface liquid; providing a channel dividingformation extending generally downwardly from an opening of the channeltowards but not to the base, so as to divide the channel into a drainageportion open for the access flow of surface liquid and a chamber portionand to define a liquid communicating portion between the drainageportion and the chamber portion below the dividing formation; andproviding at least one buoyant barrier member received in the chamberportion to be selectively moveable between a first position within thechannel to a second position where the wall member at least partiallyextends from the channel; whereby liquid level in the chamber portionfollows liquid level in the drainage portion to allow, in use, varyinglevels of liquid in the channel to move the barrier member reversiblybetween the first position and the second position.
 21. A methodaccording to claim 20 comprising the steps of: providing a channelmodule comprising: a channel lining having a base and side wallsextending downwardly from a surface so as to be adapted to collect andtransfer surface liquid; a channel dividing formation extendinggenerally downwardly from an opening of the channel lining towards butnot to the base, so as to divide the channel lining into a drainageportion open for the access flow of surface liquid and a chamber housingand to define a liquid communicating portion between the drainageportion and the chamber portion below the dividing formation; and atleast one buoyant barrier member received in the chamber housing to beselectively moveable between a first position within the channel liningand a second position where the barrier member at least partiallyextends from the channel lining; and installing the channel module intoa sub-surface channel excavation.
 22. A method according to claim 20comprising the steps of: inserting a channel dividing formationextending generally downwardly from an opening of the channel towardsbut not to the base, so as to divide the channel into a drainage portionopen for the access flow of surface liquid and a chamber portion and todefine a liquid communicating portion between the drainage portion andthe chamber portion below the dividing formation; and slideably mountingat least one buoyant barrier member in the chamber portion to beselectively moveable between a first position within the channel to asecond position where the barrier member at least partially extends fromthe channel; whereby liquid level in the chamber portion follows liquidlevel in the drainage portion to allow, in use, varying levels of liquidin the channel to move the barrier member reversibly between the firstposition and the second position.